(a) Field of the Invention
This invention relates to liquid containers and more particularly, but not by way of limitation, to a liquid container for mounting on a vehicle such as a bicycle wherein the liquid in the container is cooled using evaporative cooling.
(b) Discussion of Prior Art
There are many bicycle-type water bottles currently available on the market. The most popular water bottle design is a squeezable bottle of a generally cylindrical shape which can be readily grasped by the cyclist and removed from a bicycle cage which is mounted to the bicycle frame. Once the bottle is in hand, a valve in the top of the bottle is opened and the cyclist squeezes the bottle to expel the water through the valve.
The typical water bottle used by the cyclist is made of plastic with a single shell wall. A drawback of the single shell wall design is that this type construction provides poor insulation and the liquid inside the bottle is undesirably warmed by the sun or a high ambient temperature during a summer bicycling season. To make matters worse, a heat transfer rate to the inner liquid is significantly increased by a convective heat transfer caused by the flow of hot air against the outside of the bottle.
Heretofore, a typical solution attempted by most cyclists is to fill the bottle with ice or the freeze the entire bottle before leaving for a bicycle ride. Unfortunately, the above mentioned high heat transfer rate makes this solution effective for only a relatively short time compared to the length of average bicycle ride. This also has the disadvantage of requiring the cyclist to have the forethought to freeze the bottle and/or ice several hours before the bicycle ride. Further, this solution also has a disadvantage of providing the cyclist the coldest water at the beginning of the ride when it is least needed and the warmest water at the end of the ride when it is most undesirable. Finally, an ice-cold drink of water may not be desirable on an extremely hot day. It would be more preferable to have water chilled to 20 to 30 degrees Fahrenheit below the ambient temperature so as not to unduly chill the cyclist's throat.
A common solution offered by bottle manufactures is to provide a bicycle bottle with one or more layers of insulating material to reduce the heat transfer rate to the liquid inside the bottle. A significant disadvantage of such a design is that the inner volume of the liquid must be reduced in order for the insulated bottle to fit into a standard hanging device. In addition, the high heat transfer rates are only marginally reduced and the cyclist is still left with undesirable warmed water at the end of the bicycle ride.
An alternate solution recently introduced in the market is to provide a built-in compartment for a frozen gel-pack. With this design the cyclist is required to freeze the gel-pack several hours before the bicycle ride and then must insert it into the bottle before leaving. This design suffers from the disadvantage that the built-in compartment for the frozen gel-pack significantly reduces the volume of the inner liquid. In addition, if an attempt is made to reduce the rate of heat transfer by adding a layer of insulation then the inner volume is reduced even further.
The principal of cooling foods and liquids by storing the same in containers of porous material which could be soaked in water is well known. For example, U.S. Pat. No. 4,380,157 describes a self-chilling dispenser for drinking fluids. This and other such designs are typically made of a rigid porous clay material and as such are not suited for bicycle travel. Alternatively, evaporative cooled water bags made of a flax material are also available in the marketplace. These, however, suffer from the disadvantage of having no clear way of being attached to a bicycle and thus are not suitable for rapid movements required in bicycle travel.
In U.S. Pat. No. 4,544,077 to Rucker, a liquid container for a bicycle is described wherein a container body includes a slot therein for allowing water to pass into contact with a exterior liner for providing evaporative cooling. A significant disadvantage of this design is that the liner has a very low liquid carrying capacity, thus the rider must inconveniently re-saturate the liner by manually opening and closing the slot at regular intervals or the evaporative cooling effect will be lost. This design also has the disadvantage that any liquid dispensed from the slot is not available for the rider to drink. In addition, the liner described in this patent is not designed to meter the liquid flow and thus if the slot is inadvertently left open, the liquid will rapidly leak out leaving the rider without water. Finally, attempts to use this design for sugary liquids such as fruit juice would cause the exterior liner to become sticky and undesirable to the touch, and thus an extensive cleaning process would be required before the next use.
In the marketplace today, there are currently two different prior art evaporatively cooled water bottles with shells which are advertised to the public. The first product is called by a brand name of "COOLSOCK". The shell of this item is made of a natural fiber such as cotton or felt encased in a sewn synthetic fabric cover. The natural fibers have the distinct disadvantage of promoting mold or mildew growth if left in a saturated condition. In addition, there is no convenient way of attaching the fabric cover to the natural fiber, thus the cover easily moves relative to the fiber thereby making it subject to tearing and bunching. Also, the natural fiber provides no stretch. Therefore, an additional means for retaining the shell on the bottle is required, adding to the manufacturing cost. Also, natural fibers do not readily absorb and retain water as effectively as the hydrophilic foam used in the subject invention. This leads to shorter periods of performance or requires increased shell thickness which is not desirable.
The second product, called by a brand name of "RUNNIN' COOL", is an insulted water bottle which claims to have the components necessary for evaporative cooling. An insulating material, called by a brand name of "THERMOLITE", made by Dupont, is layered with a standard foam and fabric. Neither the insulating material or the foam have any hydrophilic properties and thus this product can not match the absorption and water retention capabilities of the invention described herein. This insulated water bottle relies on water condensing from the air and then evaporating to achieve a cooling effect which is ineffective as any heat removed by the evaporation is gained during condensation.
With the above in mind, none of the prior art liquid bottles and evaporatively cooled bottles with covers and shells provide a consistently cool liquid for a cyclist to drink over a duration of an average bicycle ride. Therefore, a need exists for an improvement of existing bottle construction so as to enhance bottle performance in maintaining a desired temperature of the liquid in the bottle for the duration of the bicycle ride. The subject self-chilling liquid container solves the above mentioned problems with the advantages described herein.